1. Field of the Invention
The invention relates to a load driving apparatus, and particularly to, a light-emitting diode driving apparatus and a driving method thereof.
2. Description of Related Art
Conventionally, a light-emitting diode (LED) driving apparatus is generally composed by circuits such as a control chip, a power switch and an external circuit, etc. The control chip may provide a driving signal to switch the power switch, so that the LED(s) may emit light according to a current generated by switching of the power switch. In order to achieve a high contrast ratio with conventional LED dimming technologies, a Pulse Width Modulation (PWM) dimming technology is generally used by the driving apparatus. A dimming principle thereof is to control a time proportion/ratio of the LED(s) in full brightness and full dark state by adjusting a duty cycle of a PWM dimming signal, so as to complete a dimming operation.
Generally, in illuminating applications of LED, a voltage is provided to turn on or activate an LED driving apparatus. After the LED driving apparatus is turned on or activated, a partial of electrical energy used in LED operations are to be retrieved and fed back as power for the LED driving apparatus. However, when LED(s) is/are in a full dark state, since time for LED(s) being turned on is shorten, time and energy to be provided to the LED driving apparatus is relatively less, accordingly. Therefore, when LED(s) is/are in full dark state, the control chip in the LED driving apparatus may not operate normally due to insufficient power. Generally, a large external capacitor is required for providing power to the control chip, so that the control chip may operate normally through when LED(s) is/are in full dark state. Nevertheless, the LED driving apparatus may still stop operating when said capacitor is insufficient. In addition, if increasing the capacitance of the large external capacitor, not only the processing cost is increased, but also an area required for a printed circuit board (PCB) is increased.